The case was taken by the American Civil Liberties Union (ACLU), with the organisation's Lee Gelernt saying: “This ruling is an enormous victory for parents and children who thought they may never see each other again."

In a separate case, 17 US states are suing the Trump administration over the separation of migrant families.

California Attorney General Xavier Becerra said: "We are taking the Trump Administration to court because the safety, security and well-being of our children is too important to be threatened by a heartless political maneuver."

Yesterday the US President's travel ban - affecting mostly Muslim countries - has been backed by the country's highest court.